Doffing guns are typically used in the texturing areas of textile facilities to doff yarn when threading up the texturing machines. In a typical doffing gun, a thread is sucked through the inlet suction tube and discharged out the exhaust side through a diffuser cone into a yarn collecting sack. Suction in the gun is generated by a draft tube ejector whereby compressed high-velocity air enters through the gun handle and mixes with the secondary, low-velocity fluid present in the ejector. Through this mixing or aspirating, a major portion of the momentum of the primary fluid is imparted to the secondary fluid, resulting in an air vacuum.
Doffing guns present in the prior art typically have high noise levels associated therewith. For example, two known, commercially available doffing guns built by American Barmag Co. (Barmag) and Maybry Industries of North Carolina, as well as an in-house unit of Burlington-Madison Yarn Company (BMYC) all have noise levels significantly higher than a sound specification for auxiliary sound sources. In addition, they often have inefficient vacuums, which require significant amounts of compressed air. Because the doffing unit must be capable of removing yarn at a speed equal to or greater than the machine yarn speed, the amount of air suction is very important for overall performance.